Electronic device and airflow adjustment member

ABSTRACT

An electronic device has a board, a heat producing component mounted on the board, a connector mounted on the board and allowing a module component to be fitted thereto, a chassis housing the board, and an air blower configured to cause air to flow through the chassis. Additionally, an airflow adjustment member including a guide portion is placed upstream, in a flow direction of the air, of the heat producing component and the connector, the guide portion being configured to guide part of air flowing toward a region where the connector is placed to a region where the heat producing component is placed.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority of theprior Japanese Patent Application No. 2012-156617, filed on Jul. 12,2012, the entire contents of which are incorporated herein by reference.

FIELD

The embodiments discussed herein are related to an electronic device andan airflow adjustment member.

BACKGROUND

In an electronic device such as a server, components such as a memoryand a DDC (DC-DC converter) are modularized, and those modularizedcomponents are fitted to connectors on a motherboard according to anadopted device configuration. Modularized components are called modulecomponents hereinbelow.

In a server, components such as a central processing unit (CPU) and amemory produce heat while the server is operated. When the temperatureof a component such as the CPU or the memory exceeds an allowable upperlimit temperature set for that component, malfunction or failure mightoccur. For this reason, in a general server, a cooling fan or the likecauses cooling air (also called air below) to flow through a chassis ofthe server to cool the components therein and discharges heat inside theserver to the outside of the chassis.

[Patent Document 1] Japanese Laid-open Utility Model Publication No.07-42181

In the server configured to cool its components in the chassis by use ofthe cooling fan or the like, the flow of the cooling air (called anairflow below) changes when the configuration of the module componentsmounted in the chassis changes. This might result in a poor coolingefficiency.

SUMMARY

According to an aspect of the technique disclosed, provided is anelectronic device including: a board; a heat producing component mountedon the board; a connector mounted on the board and including a latchlever configured to allow a module component to be fitted to and removedfrom the connector; a chassis housing the board; an air blowerconfigured to cause air to flow through the chassis; and an airflowadjustment member placed upstream, in a flow direction of the air, ofthe heat producing component and the connector, and including a guideportion configured to guide part of air flowing toward a region wherethe connector is placed to a region where the heat producing componentis placed. The latch lever is located at such a position as to restrictat least part of a flow of the air toward the region where the connectoris placed.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and arenot restrictive of the invention.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view illustrating an example of a motherboard ofa server;

FIG. 2 is a top view of the motherboard in FIG. 1;

FIG. 3 is a perspective view of a server according to a firstembodiment;

FIG. 4 is a perspective view illustrating a motherboard of the server inFIG. 3;

FIG. 5A is a perspective view of an airflow adjustment member, and FIG.5B is a perspective view illustrating a back side of the airflowadjustment member in FIG. 5A;

FIG. 6 is a schematic diagram illustrating the positions of guideportions of the airflow adjustment member;

FIG. 7 is a schematic diagram illustrating the flow of air blown by acooling fan;

FIG. 8 is a schematic diagram illustrating the flow of air passing underthe guide portion and entering a memory-mounted region;

FIGS. 9A to 9C are diagrams illustrating a memory board connector;

FIGS. 10A and 10B are diagrams illustrating a positional relationbetween the airflow adjustment member and the connector;

FIG. 11 is a diagram illustrating a positional relation between a latchlever and the guide portion;

FIG. 12 is a plan view illustrating the sizes of the portions of theairflow adjustment member;

FIG. 13 is a diagram illustrating temperature measurement positions;

FIG. 14 is a diagram illustrating temperature measurement results;

FIG. 15 is a plan view of a motherboard of a server according to asecond embodiment; and

FIG. 16 is a perspective view illustrating a state in which memoryboards and DDC boards are fitted onto the motherboard in FIG. 15.

DESCRIPTION OF EMBODIMENTS

Before embodiments are described, a prelude for facilitating an easyunderstanding of the embodiments is given below.

FIG. 1 is a perspective view illustrating an example of a motherboard ofa server, and FIG. 2 is a top view of the motherboard in FIG. 1. Forconvenience of description, two orthogonal directions denoted by X and Yin FIG. 2 are called an X direction and a Y direction, respectively.

CPUs and other components are mounted on a motherboard 10. Since theCPUs produce a large amount of heat upon operation, a heat sink 11formed of a metal or the like having excellent heat conductivity isattached above each of the CPUs. Heat produced by the CPU moves to theheat sink 11 and is then dissipated to the air through the heat sink 11.

A plurality of memory board connectors (memory slots) 13 are arranged onthe motherboard 10. Memory boards 12 are fitted to these connectors 13according to an adopted device configuration. The memory boards 12 arean example of a module component.

In the example illustrated in FIGS. 1 and 2, the plurality of connectors13 are arranged at positions sandwiching each of the CPUs (the heatsinks 11). The connectors 13 are arranged side by side in the Xdirection with their longitudinal positions in the Y directioncoinciding with each other.

Hereinbelow, a CPU-mounted region refers to a region on the motherboardwhere the CPU and the heat sink 11 are placed, and a memory-mountedregion refers to a region where the memory board is placed.

A plurality of cooling fans 14 are arranged along one side of themotherboard 10, the one side being in parallel with the X direction.These cooling fans 14 introduce air of a relatively low temperature intoa chassis of the server to cool the heat sinks 11 and the memory boards12. The white arrows in FIG. 2 indicate a flow direction of the air.

As mentioned earlier, in an electronic device such as a server, thenumber of mounted module components differs according to the deviceconfiguration. Hence, the airflow through the chassis changes dependingon the number of mounted module components.

For example, if the memory boards 12 are fitted to all of the connectors13 on the motherboard 10, the airflow is blocked due to ventilationresistance by the memory boards 12. Consequently, the amount of airflowing into the memory-mounted regions decreases, so that a relativelylarge amount of air flows into the CPU-mounted regions.

In contrast, if a few memory boards 12 are mounted, the ventilationresistance by the memory boards 12 is low. This results in increasingthe amount of air flowing into the memory-mounted regions, so that arelatively small amount of air flows into the

CPU-mounted regions. For this reason, the temperatures of the CPUs tendto be higher when a small number of memory boards 12 is mounted thanwhen a large number of memory boards 12 is mounted.

In a general server, the rotation speed of the cooling fans 14 iscontrolled according to the temperatures of the CPUs so that thetemperatures of the CPUs will not exceed an allowable upper limit. Inthis case, however, the rotation speed of the cooling fans 14 isincreased when a small number of memory boards 12 is mounted;consequently, power consumption increases.

To avoid this, when a small number of memory boards 12 are mounted, adummy component having almost the same shape as the memory board 12 maybe fitted to an empty connector to prevent the change in the ventilationresistance. However, such a measure prefers fitting and unfitting of thedummy component when the device configuration is changed. This not onlycomplicates work, but also increases cost for manufacturing and storageof the dummy component.

In embodiment below, a description is given of an electronic device andan airflow adjustment member which may make a ventilation resistancesubstantially constant irrespective of the number of mounted modulecomponents and may efficiently cool heat-producing components withoutusing dummy components.

First Embodiment

FIG. 3 is a perspective view of a server according to a firstembodiment, and FIG. 4 is a perspective view illustrating a motherboardof the server in FIG. 3.

For convenience of description, two orthogonal directions denoted by Xand Y in FIGS. 3 and 4 are called an X direction and a Y direction,respectively. In addition, in this embodiment, in the server illustratedin FIG. 3, the upstream side and downstream side of a flow direction ofair are called a front side and a rear side, respectively. In thisembodiment, the electronic device is a server, and the module componentis a memory board.

As illustrated in FIG. 3, a server 20 has a chassis 21 and a motherboard22 housed inside the chassis 21. The chassis 21 is provided at its frontside with a front panel 25 a and at its rear side with a rear panel 25b. These panels 25 a and 25 b are each provided with vents. HDD cages 26a and an operation panel unit 26 b are placed between the front panel 25a and the motherboard 22. A hard disk drive is to be placed inside eachHDD cage 26 a.

CPUs 30 and other electronic components are mounted on the motherboard22. A heat sink 31 formed of a metal having excellent heat conductivityis attached above each CPU 30. The heat sink 31 is provided with manyfins extending in the X direction, and air flowing between those finsdischarges heat produced by the CPU 30 to the outside.

Moreover, a plurality of memory board connectors (memory slots) 33 arearranged on the mother board 22. Memory boards 32 are fitted to thememory board connectors 33 according to an adopted device configuration.Each memory board 32 is a board on which one or a plurality ofsemiconductor memory devices (large-scale integrated memory (LSI)) aremounted.

In the example illustrated in FIGS. 3 and 4, the plurality of memoryboard connectors 33 are arranged on both sides, in the X-direction, ofeach CPU (heat sink 31). These connectors 33 are arranged side by sidein the X direction with their longitudinal positions in the Y directioncoinciding with each other. FIGS. 3 and 4 illustrate a state where thememory boards 32 are fitted to all the connectors 33.

A plurality of cooling fans 34 (four of them in FIGS. 3 and 4) arearranged along one side of the motherboard 22 which is at the front.These cooling fans 34 cause air to flow in the Y direction in FIGS. 3and 4 to cool the CPUs 30 (heat sinks 31) and the memory boards 32. Forexample, the motherboard 22 has a sensor configured to detect thetemperatures of the CPUs 30 and a controller configured to control therotation speed of the cooling fans 34 according to an output of thesensor. When the temperatures of the CPUs 30 are high, the rotationspeed of the cooling fans 34 is increased.

A plurality of expansion card slots 36 are arranged at a rear portion ofthe motherboard 22. Expansion cards 37 according to the deviceconfiguration are fitted to the expansion card slots 36. In addition,communication connectors 38 and the like are provided at a rear portionof the motherboard 22. The server 20 communicates with anotherelectronic device via a communication cable attached to thecommunication connector 38.

The motherboard 22 is an example of a board, the CPU 30 is an example ofa heat producing component, and the cooling fan 34 is an example of anair blower.

In general, the CPU 30 produces more heat than the memory board 32.Thus, in order to accomplish reduction in power consumption bydecreasing the rotation speed of the cooling fans 34, it is important toefficiently cool the CPU 30. Hence, in this embodiment, an airflowadjustment member 40 is placed windward of the CPU-mounted regions andthe memory-mounted regions.

FIG. 5A is a perspective view of the airflow adjustment member 40, andFIG. 5B is a perspective view of a back side of the airflow adjustmentmember 40 in FIG. 5A.

As illustrated in FIGS. 5A and 5B, the airflow adjustment member 40 hasa support portion 41, guide portions 42, and attachment portions 43. Thesupport portion 41 has a flat plate shape, and the guide portions 42 aretriangular and arranged on the lower face of the support portion 41. Theattachment portions 43 are provided at both ends and the center portion,in the longitudinal direction, of the support portion 41, and are usedto fix the airflow adjustment member 40 to a predetermined position onthe motherboard 22.

In this embodiment, the airflow adjustment member 40 is formed ofpolycarbonate. Note, however, that the airflow adjustment member 40 maybe formed by a material other than polycarbonate.

The airflow adjustment member 40 is placed such that the trianglevertices of the guide portions face the cooling fans 34. When theairflow adjustment member 40 is placed at the predetermined position onthe motherboard 22, a rear end portion of the support portion 41 coverfront end portions of the connectors 33 from above.

As FIG. 6 schematically illustrates, when seen from the windward, theguide portions 42 are located at positions corresponding to thememory-mounted regions 46, and are not provided at positionscorresponding to the CPU-mounted regions 45. Thus, as illustrated inFIG. 7, part of air blown by the cooling fans 34 and flowing toward thememory-mounted regions 46 travels along inclined surfaces of the guideportions 42, merges with air blown by the cooling fans 34 and flowingtoward the CPU-mounted regions 45, and then travels to the CPU-mountedregions 45.

As illustrated in FIG. 6, there is a space between the guide portions 42and the motherboard 22. Thus, as illustrated in FIG. 8, rest of the airblown by the cooling fans 34 and flowing toward the memory-mountedregions 46 travels under the guide portions 42 and enters thememory-mounted regions 46 to cool the memory boards 32.

In this embodiment, since the airflow adjustment member 40 is placedwindward of the CPU-mounted regions 45 and the memory-mounted regions 46as described above, the CPU-mounted regions 45 are supplied with the airpreferentially over the memory-mounted regions 46. Hence, the CPUs 30may be sufficiently cooled even when the rotation speed of the coolingfans 34 is low, and therefore power consumed by the cooling fans 34 maybe reduced.

Incidentally, as seen from FIG. 8, the front end portions of the memoryboard connectors 33 are obstacles for the air having flowed under theguide portions 42. Thus, in this embodiment, the states of the front endportions of the memory board connectors 33 largely influence the flowrate of the air supplied to the memory-mounted regions 46. On the otherhand, since the ventilation resistance by the memory boards 32 issmaller than that by the connectors 33, the flow rate of air does notchange much no matter whether the memory board 32 is fitted to theconnectors 33 or not.

FIGS. 9A to 9C are diagrams illustrating the memory board connector 33.FIG. 9A illustrates a state where the memory board 32 is fitted to theconnector 33, and FIGS. 9B and 9C each illustrate a state where thememory board 32 is not fitted to the connector 33.

Both longitudinal ends of the connector 33 each have a column portion 33b configured to support an end portion of the memory board 32 and alatch lever 33 a configured to open and close by rotating about afulcrum provided to the column portion 33 b. When the memory board 32 isbeing fitted to the connector 33, the latch levers 33 a are closed tofix the memory board to the connector 33 as illustrated in FIG. 9A inorder to prevent the memory board 32 from coming off by vibration or thelike, or to prevent a contact failure and the like.

When the memory board 32 is not fitted to the connector 33, the latchlevers 33 a are generally kept open as illustrated in FIG. 9B. However,in this embodiment, whether the latch levers 33 a are kept open orclosed largely changes the flow rate of air flowing into thememory-mounted regions 46, and also changes the flow rate of air flowinginto the CPU-mounted regions 45.

In this embodiment, even while the memory board 32 is not fitted to theconnector 33, the latch levers 33 a are kept closed as illustrated inFIG. 9C. This allows the ventilation resistance by the connector 33 tobe always constant.

FIGS. 10A and 10B are diagrams illustrating a positional relationbetween the airflow adjustment member 40 and the connector 33. Asillustrated in FIG. 10A, in this embodiment, the airflow adjustmentmember 40 may be attached to the predetermined position when the latchlevers 33 a are closed. On the other hand, when the latch levers 33 aare open, the airflow adjustment member 40 comes into contact with thelatch levers 33 a as illustrated in FIG. 10B, and the airflow adjustmentmember 40 is therefore not attached to the predetermined position. Thisallows prevention of forgetting to close the latch levers 33 a.

In order to attain the effect of preventing forgetting to close thelatch levers 33 a, it is important that, as illustrated in FIG. 11, theposition of a lower end of the guide portion 42 be located lower thanposition A1 of an upper end of the closed latch lever 33 a when theairflow adjustment member 40 is attached to the predetermined position.

If the position of the lower end of the guide portion 42 is locatedlower than position A2 of an upper end of the column portion 33 b of theconnector 33, the space between the guide portion 42 and the motherboard22 is narrowed to decrease the flow rate of air supplied to thememory-mounted regions 46. For this reason, the position of the lowerend of the guide portion 42 is preferably higher than position A2 of theupper end of the column 33 b of the connector 33 when the airflowadjustment member 40 is attached to the predetermined position.

Further, in this embodiment, the guide portions 42 function as a latchlever open-close state detector configured to detect whether the latchlevers 33 a are open or closed. Alternatively, the airflow adjustmentmember 40 may be provided with a latch lever open-close state detector,separate from the guide portions 42.

As described above, in this embodiment, the airflow adjustment member 40is not placed at the predetermined position when the latch levers 33 aare open. Hence, the ventilation resistance against the air flowingunder the guide portions 42 is almost constant, irrespective of whetherthe memory board 32 is fitted to the connector 33 or not. As a result, aratio of air flowing into the CPU-mounted regions 45 to air flowing intothe memory-mounted regions 46 is almost constant.

Moreover, in this embodiment, as illustrated in FIG. 8, the rear endportion of the airflow adjustment member 40 covers the end portion ofthe memory board 32 from above. Thereby, after flowing under the guideportions 42, air travels in the longitudinal direction of the memoryboard 32 without spreading upward. This allows the memory boards 32 tobe efficiently cooled as well.

A description is given below of results of examining a change in thetemperatures of the CPUs when the memory boards are mounted and when thememory board are not mounted.

As an embodiment example, a server having a structure illustrated inFIG. 3 is prepared. The sizes of the portions of the airflow adjustmentmember 40 are as depicted in FIG. 12.

A server of a comparative example is also prepared. The server of thecomparative example has the same airflow adjustment member 40 as that ofthe embodiment example except that it does not have the guide portions42.

For each of the embodiment example and the comparative example, thetemperatures of the CPUs and the temperatures of the memory boards in acase where the memory boards (DIMM) are fitted to all the connectors aremeasured, and the temperatures of the CPUs in a case where the memoryboards are removed from all the connectors are measured. FIG. 13 depictspositions of the temperature measurements, and FIG. 14 depicts resultsof the temperature measurements.

In FIG. 13, C1 and C2 are the positions where the temperatures of theCPUs are measured, and M1 to M4 are the positions where the temperaturesof the memory boards are measured. Further, in FIG. 14, temperaturesunder “fully mounted” are temperatures measured when the memory boards(DIMM) are fitted to all the connectors, and temperatures under “withoutDIMM” are temperatures measured when the memory boards are removed fromall the connectors.

As seen from FIG. 14, in the embodiment example, the difference in thetemperatures of the CPUs between when the memory boards are mounted andwhen the memory boards are not mounted is as small as 0.4° C. to 0.5° C.In contrast, in the comparative example, the difference in thetemperatures of the CPUs between when the memory boards are mounted andwhen the memory boards are not mounted is as large as 2.1° C. to 2.5° C.

Further, the temperatures of the CPUs of the embodiment example when thememory boards are mounted are lower than those of the comparativeexample by 3.5° C. to 4.0° C., and the temperatures of the CPUs of theembodiment example when the memory boards are not mounted are lower thanthose of the comparative example by 5.5° C. to 5.7° C. Note that thetemperatures of the memory boards are almost the same in the embodimentexample and the comparative example.

As seen from the above results of the temperature measurements,irrespective of whether the memory boards are mounted or not, the CPUsare cooled more efficiently in the server of the embodiment example thanin the server of the comparative example.

Second Embodiment

FIG. 15 is a plan view of a motherboard of a server according to asecond embodiment, and FIG. 16 is a perspective view of the motherboardin FIG. 15, to which memory boards and DDC (DC-DC converter) boards arefitted. This embodiment differs from the first embodiment in that themotherboard is provided with connectors to which the DDC boards are tobe fitted, and other configurations of this embodiment are basically thesame as those of the first embodiment, and are therefore not describedagain here.

As illustrated in FIG. 15, a motherboard 51 is provided with the memoryboard connectors 33 to which the memory boards 32 are to be fitted andDDC board connectors 53 to which DDC boards 52 are to be fitted. Thememory board connectors 53 are located at DDC-mounted regions adjacentto the memory-mounted regions where the memory board connectors 33 areplaced. The DDC board 52 is a board on which one or a plurality of DDCsare mounted. Like the memory board connector 33, the DDC board connector53 is provided at its both end portions with latch levers for fixing theDDC board 52.

Similar to the first embodiment, the airflow adjustment member 40 isplaced windward of the memory board connectors 33 and the DDC boardconnectors 53. The airflow adjustment member 40 is provided with theguide portions 42 (see FIGS. 5A and 5B).

Part of air blown by the cooling fans 34 and flowing toward thememory-mounted regions and the DDC-mounted regions travels along theinclined surfaces of the guide portions 42, merges with air blown by thecooling fans 34 and flowing toward the CPU-mounted regions, and thentravels toward the CPU-mounted regions.

Rest of the air blown by the cooling fans 34 and flowing toward thememory-mounted regions and the DDC-mounted regions flows under the guideportions 42 and enters the memory-mounted regions and the DDC-mountedregions to cool the memory boards 32 and the DDC boards 52.

As described above, the technique disclosed may be used even when modulecomponents other than the memory boards 32 are used as the modulecomponents.

All examples and conditional language recited herein are intended forthe pedagogical purposes of aiding the reader in understanding theinvention and the concepts contributed by the inventor to further theart, and are not to be construed as limitations to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although one or more embodiments of thepresent invention have been described in detail, it should be understoodthat the various changes, substitutions, and alterations could be madehereto without departing from the spirit and scope of the invention.

What is claimed is:
 1. An electronic device comprising: a board; a heatproducing component mounted on the board; a connector mounted on theboard and including a latch lever configured to allow a module componentto be fitted to and removed from the connector; a chassis housing theboard; an air blower configured to cause air to flow through thechassis; and an airflow adjustment member placed upstream, in a flowdirection of the air, of the heat producing component and the connector,and including a guide portion configured to guide part of air flowingtoward a region where the connector is placed to a region where the heatproducing component is placed, wherein the latch lever is located atsuch a position as to restrict at least part of a flow of the air towardthe region where the connector is placed.
 2. The electronic deviceaccording to claim 1, wherein the latch lever opens and closes byrotating about a fulcrum provided to a column portion of the connectorlocated at an end portion of the connector on the airflow adjustmentmember side, the latch lever being configured to allow the modulecomponent to be fitted to and removed from the connector when opened,and the airflow adjustment member includes a latch lever open-closedetector configured to come into contact with the latch lever when thelatch lever is open, and thereby prevent the airflow adjustment memberfrom being placed at a predetermined position.
 3. The electronic deviceaccording to claim 2, wherein when the airflow adjustment member is atthe predetermined position, the latch lever open-close detector islocated at a position higher than the column portion of the connector.4. The electronic device according to claim 1, wherein the heatproducing component and the connector are arranged side by side in adirection intersecting the flow direction of the air sent from the airblower.
 5. The electronic device according to claim 1, wherein aplurality of the connectors are arranged side by side.
 6. The electronicdevice according to claim 1, wherein the heat producing component is aCPU, and the module component is a memory board on which a semiconductormemory device is mounted.
 7. The electronic device according to claim 1,wherein the heat producing component is a CPU, and the module componentis a DDC (DC-DC converter) board on which a DDC is mounted.
 8. Anairflow adjustment member placed inside a chassis of an electronicdevice, the airflow adjustment member comprising: a support portionhaving a flat plate shape; and a guide portion located on one ofsurfaces of the support portion and configured to guide part of airflowing along the one surface of the support portion in a directionintersecting a flow direction of the air.
 9. A method of cooling a heatproducing component in an electronic device having a board, a heatproducing component mounted on the board, a connector mounted on theboard and including a latch lever configured to allow a module componentto be fitted to and removed from the connector, a chassis housing theboard, an air blower configured to cause air to flow through thechassis, and an airflow adjustment member placed upstream, in a flowdirection of the air, of the heat producing component and the connector,and configured to adjust a flow of the air sent from the air blower, themethod comprising: guiding part of air flowing toward a region where theconnector is placed to a region where the heat producing component isplaced, by the airflow adjustment member; and restricting at least partof a flow of the air toward the region where the connector is placed, bythe latch lever.